1. Field of the Invention
This invention relates to a biodegradable composition and a foam article made therefrom.
2. Description of the Related Art
Expanded polystyrene (EPS) has become a widely used foam material because of the properties of water tolerance, thermal-resistivity, insulativity, low hygroscopicity, anti-shock, and light weight. In addition, the manufacture of EPS into foam products is simple and relatively inexpensive.
However, the EPS products are stable in natural environment and can not be degraded for hundreds of years. Discarded EPS products therefore are not recycled and result in serious environmental impact.
In order to overcome the aforesaid drawback associated with EPS, other foam polymers, such as polylactic acid (PLA) and polybutylene-1,4-succinate (PBS), are used. PLA and PBS are biodegradable polymers and have relatively mild environmental impact. However, the glass transition temperature of polylactic acid is only about 60° C., which is too low, and thereby results in poor thermal-resistivity. The foam product made from PLA may deform when used under an elevated temperature. Moreover, each of PLA and PBS has a relatively high melt index (M.I.), i.e., 4-4.5 and 4.5 respectively, that results in lower melt strength and inferior gas barrier. During manufacture of foam products made from PLA or PBS, foaming failure phenomenon appears during the foaming process and thus the yield is adversely influenced.